THE MAJOR OBJECTIVES ARE AS FOLLOWS: The major overall objective is to apply the rapid enzyme inactivation technique utilizng microwave radiation which we have pioneered and developed to study brain metabolism in vivo. We have designed and are using microwave equipment which is able to completely inactivate rat brain enzymes within 1.5 seconds and mouse brain enqymes within 300 milliseconds. As a consequence of the methods, uniformity and speed of inactivation, we are able to measure the concentrations of metabolites and neurohormones in brain parts. These values should closely reflect those existing during life. A further objective is to expand and extend the basic preliminary information on the levels of labile metabolites and neurohormones in whole brain to that of brain parts. A further objective is to utilize this basic information and techniques to study the effect of drugs on the neurochemistry of the brain. The next objective is to further refine and develop the microwave system to attain a more rapid inactivation - that is to continue our orderly sequence which has been (1) 11 sec., (2) 6 sec., (3) 1.5 sec. and (4) 300 m sec. and to adapt the present system to use with an unrestrained animal, thus reducing the stress component. BIBLIOGRAPHIC REFERENCES: The development, construction and use of a microwave heating instrument to facilitate the study of rapidly metabolized compounds in the central nervous system. William B. Stavinoha, Arvind T. Modak, Susan T. Weintraub and Andrew P. Deam, Department of Pharmacology, The University of Texas Health Science Center at San Antonio, Texas 78284. Presented at the Society of Experimental Biology and Medicine Meeting, (1975). Rate of accumulation of acetylcholine in brain regions of rats following inhibition of cholinesterase. Arvind T. Modak, Susan Weintraub, Timothy McCoy, William B. Stavinoha, (SPON: Stephen Koslow) University of Texas Health Science Center, San Antonio, Texas 78284. Transactions of the Amerc. Soc. for Neurochem., 6:140 (1975).